Osiris Therapeutics Inc. (OSIR) surged 15 percent in early trading after the company said it won the world’s first approval for a stem-cell drug, gaining clearance in Canada to sell Prochymal for a disease that can attack patients who received bone-marrow transplants. Osiris rose 79 cents to $6.05 at 6:21 a.m. New York time. The shares had fallen 28 percent in the 12 months before today. Prochymal was approved for the treatment of acute graft versus host disease in children for whom steroids haven’t worked, the Columbia, Maryland-based company said yesterday in a statement. Steroids have a 30 percent to 50 percent success rate, and severe GvHD can be fatal in 80 percent of cases, according to the company.